Cold Crashing

[Bus06]

Quick question... What is this cold crashing that I keep hearing about? I am hearing about people doing it to beer when they post reviews on recipe kits and I am wondering if it is something that makes the beer better. Also wondering about how to do it.

 

[McKnuckle]

Once the beer has finished fermenting and reached final gravity, move the primary fermenter to a cold space (close to freezing is best). This helps it clarify and stabilize prior to either packaging or moving it to a secondary vessel. Yeast, proteins, and other compounds become heavy in the cold temps and drop to the bottom of the fermenter, allowing you to rack clear beer to the next container.

That's pretty much it.

 

[gm12812]

Should be emphasized that YEAST are dropping (with the other things McKnuckle mentioned.)
So if you bottle, you should be careful with cold crashing. Lower temps remove/kill yeast and you'll need that yeast to ferment your priming sugar and carbonate your beer.

If you keg, cold crashing is a no brainer!

 

[NothingRhymesWithCurtiss]

Should be emphasized that YEAST are dropping (with the other things McKnuckle mentioned.)
So if you bottle, you should be careful with cold crashing. Lower temps remove/kill yeast and you'll need that yeast to ferment your priming sugar and carbonate your beer.

I bottle and cold crashed for the first time and saw my bottles taking longer to carb up and posted about it here: https://www.homebrewtalk.com/showthread.php?t=594561.

I got some good suggestions in the replies.

 

[brew703]

Should be emphasized that YEAST are dropping (with the other things McKnuckle mentioned.)
So if you bottle, you should be careful with cold crashing. Lower temps remove/kill yeast and you'll need that yeast to ferment your priming sugar and carbonate your beer.

If you keg, cold crashing is a no brainer!

Not exactly accurate. I bottle and cold crash every beer I make. I also add gelatin once my temps get to 40 degrees. Never had a carbonation issue with cold crashing or adding gelatin with the exception of an IPA I did which took almost a month to fully carb.

 

[Redlantern]

I have cold crashed for as long as 9 days and had things carb up just fine. crashed at 38°F

Pretty much now will gelatin for 24 hrs then crash for three days before packaging any lighter colored beer I make. Never had a problem with carbonation.

 

[btbnl]

The other cold-crashing bugbear is sucking air back into the fermentor as it cools and the associated risks of oxygenation, especially for hoppy beers. Some people even attach a balloon full of CO2 to the air lock to avoid this.

Yeast, proteins, and other compounds become heavy in the cold temps

As a physicist, my head just assploded. Things drop out of suspension more quickly the colder the beer, but nothing is becoming heavier!

 

[McKnuckle]

My apologies for the scientific faux pas. Denser, then?

 

[seabrew8]

I have cold crashed for as long as 9 days and had things carb up just fine. crashed at 38°F

Pretty much now will gelatin for 24 hrs then crash for three days before packaging any lighter colored beer I make. Never had a problem with carbonation.

I don't understand this. You gelatin for 24 hours?

 

[Redlantern]

I don't understand this. You gelatin for 24 hours?

at the end of the dry hop time period and roughly 24 hours before cold crash, I add the gelatin.

mix 1/2 pack of unflavored gelatin in 1-1/2 cup of water heated to about 150°F. Allow to stand for 10 min or so and add to fermenter.

24 hours later, I place my fermentor in the keezer for about three days.

Results are wonderful.

 

[seabrew8]

at the end of the dry hop time period and roughly 24 hours before cold crash, I add the gelatin.

mix 1/2 pack of unflavored gelatin in 1-1/2 cup of water heated to about 150°F. Allow to stand for 10 min or so and add to fermenter.

24 hours later, I place my fermentor in the keezer for about three days.

Results are wonderful.

So you add gelatin in warm beer? If it works don't fix it. I usually wait 12-24 hours for the beer to cool down before i add gelatin.

But reading this i will probably just add it the sametime i put the fermenter in the fridge.

 

[Redlantern]

To me, (just a guess) the gelatin seems to diffuse better through the warm beer and does not settle as fast. Once it has had a chance to diffuse, I crash it.

Only a few batches have been done this way, but I think it works a little better. Then again, I have been improving my process of monitoring and managing pH and the like, so too many variables are at play. But like you said - if it ain't broke, don't fix it.

 

[brew703]

I have added gelatin at 50* and at 40*. Didn't really notice any difference. Once I get my temps to 35-38 degrees then I usually leave at that temp for 36 hrs then bottle.

 

[seabrew8]

To me, (just a guess) the gelatin seems to diffuse better through the warm beer and does not settle as fast. Once it has had a chance to diffuse, I crash it.

Only a few batches have been done this way, but I think it works a little better. Then again, I have been improving my process of monitoring and managing pH and the like, so too many variables are at play. But like you said - if it ain't broke, don't fix it.

I just use one half of a pack and one half cup of water for gelatin. Just heat it in the microwave for about a minute in total for 4 or 5 intervals. The stuff works very fast and well.

 

[Bus06]

Thank you everyone for all of the input, I really do appreciate and I love this forum so much information out there.

 

[mattdee1]

In my experience, there is definitely truth to the notion that cold crashing causes the carbonation to take longer. What I eventually realized was, once you take the extra few days needed for cold crashing and gelatin in the fermentor, and the extra few days needed to carbonate as a result, and the annoyance of having to keep intervening on your beer, you might as well just get that beer in the bottle right after it's done fermenting and let it run on autopilot. Let it sit for a week at room temp to carbonate, put it in the fridge, and forget about it until it's ready to drink. In doing so, you're essentially moving the "clarifying" step to the bottle as the packaged beer lagers in the fridge. The overall duration between brew day and drinking a clear brew will be about the same, but you fast track getting the beer out of its attention-needing phase and you free up your equipment (chamber and fermentors) sooner, which enables you to move on to the next brew.

Of course, for this process to work to its fullest you kind of need a dedicated beer fridge that can hold a full batch of bottles for the lagering phase--otherwise you'll have to lager them in batches, which takes a lot longer. It's worth mentioning, though, that the beer will still taste fine without the extended lagering.

There might be a bit more gunk on the bottom of the bottle when you skip cold crashing in the fermentor but there will always be some, and if you pour to a glass it hardly matters anyway.

 

[Bus06]

In my experience, there is definitely truth to the notion that cold crashing causes the carbonation to take longer. What I eventually realized was, once you take the extra few days needed for cold crashing and gelatin in the fermentor, and the extra few days needed to carbonate as a result, and the annoyance of having to keep intervening on your beer, you might as well just get that beer in the bottle right after it's done fermenting and let it run on autopilot. Let it sit for a week at room temp to carbonate, put it in the fridge, and forget about it until it's ready to drink. In doing so, you're essentially moving the "clarifying" step to the bottle as the packaged beer lagers in the fridge. The overall duration between brew day and drinking a clear brew will be about the same, but you fast track getting the beer out of its attention-needing phase and you free up your equipment (chamber and fermentors) sooner, which enables you to move on to the next brew.

Of course, for this process to work to its fullest you kind of need a dedicated beer fridge that can hold a full batch of bottles for the lagering phase--otherwise you'll have to lager them in batches, which takes a lot longer. It's worth mentioning, though, that the beer will still taste fine without the extended lagering.

There might be a bit more gunk on the bottom of the bottle when you skip cold crashing in the fermentor but there will always be some, and if you pour to a glass it hardly matters anyway.

That's what I've done one the last couple of brews and they turned out pretty darn good. I just bottled them and waited. What is the Gelatin? I don't understand that whole process.

 

[seabrew8]

Gelatin is a simple way to get commercial quality clearness in maybe 1 to 3 weeks- depends on brewday of course. Really good at chill haze also.

Try making 2 of the same beers one with gelatin for 5 days after you cool the bucket down in a fridge and the other just keep it at room temps for 5 days. Wait 10 days before you change the environment.

- First batch gelatin for 5 days but ferment for 10 days first.
- 2nd batch ferment at room temp for 15 days. No Gelatin.

Pick one.

 

[MagicMatt]

My apologies for the scientific faux pas. Denser, then?

Not quite. It's simply precipitation of solids. Take a certain amount of liquid, warm it up, and you can dissolve more solids into that same volume at a colder temp. Then, if you take that same warm liquid and cool it down, the amount of dissolved solids that it can contain will decrease. Those solids will precipitate, or re-solidify and fall out.

 

[seabrew8]

nnnnnnn ooooooooooooooooooooooooooooooo

 

[bleme]

I have cold crashed in a fridge, like most people, and gotten good results but I prefer to cold crash in an ice bath. It is much faster and turns the trub into a peanut butter consistency, making siphoning a breeze! It would be cost prohibitive for a lot of people, but I get free ice from work.

 

[swampbrewcrew]

I didn't cold crash until I started kegging but I've noticed a difference. I only use a secondary for beers that are going to bulk age for awhile. I leave as much trub in the kettle as I can, but cold crashing a week before transferring to the keg has been producing some real clear beers.

 

[MagicMatt]

I have cold crashed in a fridge, like most people, and gotten good results but I prefer to cold crash in an ice bath. It is much faster and turns the trub into a peanut butter consistency, making siphoning a breeze! It would be cost prohibitive for a lot of people, but I get free ice from work.

I think most of us cold crash in a freezer, not a fridge. A freezer can get a heck of a lot colder than ice water or a fridge. Water is definitely a better conductor than air, so by that measure ice water will chill faster than a fridge/freezer at 32°F, but I'm not sure that ice water will chill faster than a freezer set on 0°F.

 

[Berchabar]

So whats the final answer on the suckback? Glass carboy will it break? Bottle of vodka or star san on the blow off tube?or just leave the top open? What do you guys do

 

[trav77]

I put cheap vodka in the airlock because I cold crash with a deep freezer. Starsan will freeze.

 

[Berchabar]

I put cheap vodka in the airlock because I cold crash with a deep freezer. Starsan will freeze.

So then you dont worry about it getting sucked back in.

I also am going to use a freezer witha an inkbird at about 32f

 

[day_trippr]

If you use an S-lock there is no suck-back.

Cheers!

 

[GPP33]

If you use an S-lock there is no suck-back.

Cheers!

Yes there is. It just bubbles in both directions so it doesn't suck the liquid back. It'll suck plenty of air in though.

 

[Redlantern]

For a carboy, instead of a stopper and airlock, I use a rubber glove and a rubber band. Works great.

For my Brewbucket, I use a 3/4" tube and the blow off hose is only an inch deep in the star-san. No way liquid can be sucked all the way back up the tube that way. If air does get in, I have convinced myself that percolating through the star-san had to do something to help out (fingers crossed)

In either case, some air gets in anyway. Would love to install a ball-lock fitting on my brewbucket lid and keep it sealed, then use the CO2 to push the beer out.....

 

[MagicMatt]

I use a 3/4" tube and the blow off hose is only an inch deep in the star-san. No way liquid can be sucked all the way back up the tube that way.

Don't be so sure. I've used a 3ft piece of 1" ID tubing for my blow off and it sucked back a good pint or two of sanitizer into my carboy once when I forgot to remove it and cap the carboy.

 

[Redlantern]

Don't be so sure. I've used a 4ft piece of 1" ID tubing for my blow off and it sucked back a good pint or two of sanitizer into my carboy once when I forgot to remove it and cap the carboy.

Depends on the volume. I do not even have two pints in my blow off. No reason to have a ton of actual liquid. or at least no reason to have the tube all the way to the bottom. If it is only an inch deep in a mason jar then none will get sucked up

 

[trav77]

So then you dont worry about it getting sucked back in.

I also am going to use a freezer witha an inkbird at about 32f

Yup. I'm not really on this super paranoid about oxidation train. Not saying it's not an issue but i only keep 2 kegs on tap at a time so they turn over pretty quick. No noticeable issues.

 

[trav77]

Also if you are using a thermowell make sure you have a 2 stage controller with a heat source (I use a brew belt). Otherwise your freezer can overshoot and freeze your beer. If your controller temp probe is measuring ambient then less of an issue.

 

[btbnl]

Time for some math:

Assuming that you're cold-crashing from around 70F to just above freezing, the volume of the gas in the head-space will shrink by about 7%, and of the beer by about 0.2%.

As a specific example, a 6G fermentor with 5G of beer will suck back ([6-5] x 0.07 + 5 x 0.002) = 0.08G, or about 2/3 pint.

So if you wanted to use your blow-off solution as a reservoir without sucking any liquid all the way back into the fermentor, you'd need at least 8 feet of 1/2" diameter tubing.

FWIW I've put together a little spreadsheet here to calculate the total suck-back volume and the corresponding line-length for user-specified fermentor and beer volumes and blow-off tube diameter.

 

[MagicMatt]

Time for some math:

Assuming that you're cold-crashing from around 70F to just above freezing, the volume of the gas in the head-space will shrink by about 7%, and of the beer by about 0.2%.

As a specific example, a 6G fermentor with 5G of beer will suck back ([6-5] x 0.07 + 5 x 0.002) = 0.08G, or about 2/3 pint.

So if you wanted to use your blow-off solution as a reservoir without sucking any liquid all the way back into the fermentor, you'd need at least 8 feet of 1/2" diameter tubing.

FWIW I've put together a little spreadsheet here to calculate the total suck-back volume and the corresponding line-length for user-specified fermentor and beer volumes and blow-off tube diameter.

I don't have time to check the actual math here (it's pretty simple but I'm about to leave), but plugging my numbers into your calculator does not agree with my experience. As stated previously, I use 1" ID hose and have had over a pint get sucked back. 6.5 gallon carboy, 5.5 gallon batch, 70°F to 32°F. Your calculator says I would only need 2.03 ft of hose to prevent suckback, but mine is 3ft and it happened.

 

[doug293cz]

I don't have time to check the actual math here (it's pretty simple but I'm about to leave), but plugging my numbers into your calculator does not agree with my experience. As stated previously, I use 1" ID hose and have had over a pint get sucked back. 6.5 gallon carboy, 5.5 gallon batch, 70°F to 32°F. Your calculator says I would only need 2.03 ft of hose to prevent suckback, but mine is 3ft and it happened.

"Volume" drop due to temp change from 68˚F to 32˚F is indeed 7.3% (293.15 / 273.15 = 1.07322.) However, the temp induced "volume" drop is not the whole story. Prior to cold crashing, the partial pressure of CO2 in the headspace is 14.7 psi. Cooling increases the solubility of CO2 in the beer, and if allowed to come to equilibrium, the CO2 partial pressure would drop to ~8.7 psi. The loss of 6 psi pressure in the headspace needs to be made up by air suck back. So for 1 gal headspace, you need to suck back 6 / 14.7 = ~ 0.41 gal of air. How much you actually suck back will depend on how long you cold crash.

Brew on

 

[btbnl]

"Volume" drop due to temp change from 68˚F to 32˚F is indeed 7.3% (293.15 / 273.15 = 1.07322.) However, the temp induced "volume" drop is not the whole story. Prior to cold crashing, the partial pressure of CO2 in the headspace is 14.7 psi. Cooling increases the solubility of CO2 in the beer, and if allowed to come to equilibrium, the CO2 partial pressure would drop to ~8.7 psi. The loss of 6 psi pressure in the headspace needs to be made up by air suck back. So for 1 gal headspace, you need to suck back 6 / 14.7 = ~ 0.41 gal of air. How much you actually suck back will depend on how long you cold crash.

Brew on

Good point! I've updated the calculator also to include the absorption, which is almost always the dominant effect if the system is left to reach equilibrium. In MagicMatt's case he'd need about 12 feet of 1" line, and 3 feet of line would allow up to 3 pints of suck back!

 

[MagicMatt]

Wow.

You know, for a second there I almost starting contemplating how to get 12ft of hose in there. Lol, yeah, not going to happen. I actually rarely even need blow offs any more with keen temp control, and now I always put a solid bung in when cold crashing.

Actually, funny I say that because I just put a blow off on a carboy from this weekend, but only because it was a 5.75 gallon batch and didn't realize until I was done boiling that I only had empty 5 and 6 gallon carboys left. So I only had a couple of inches of headspace in the 6g. It got close, but looks like I may not have needed it anyway.

 

[day_trippr]

Yes there is. It just bubbles in both directions so it doesn't suck the liquid back. It'll suck plenty of air in though.

Duh. Of course.
But that isn't what "suck-back" has always been taken to mean.

fwiw, here's how I cold-crash...



Cheers!

 

[bleme]

I think most of us cold crash in a freezer, not a fridge. A freezer can get a heck of a lot colder than ice water or a fridge. Water is definitely a better conductor than air, so by that measure ice water will chill faster than a fridge/freezer at 32°F, but I'm not sure that ice water will chill faster than a freezer set on 0°F.

I use fridge/freezer interchangeably because both are run through my temp controllers. I haven't tried cold crashing with my freezer set at 0F because I don't want to freeze my beer. I have done it with wort before, when I forgot to bring ice home though. It took almost 2 hours to get to pitching temp, while ice water will get it there in 15 minutes.